1. Field of the Invention
This invention pertains to an exercise apparatus, and more particularly, to an apparatus for exercising the abdominal muscles in contraction and for elongating the spine without placing undue stress on the muscles in the lower back.
2. Description of the Prior Art and Objectives of the Invention
Situps have long been a popular exercise for strengthening and toning the abdominal muscles. Typically, a person performing a situp lies with the back and feet on a flat surface, and with the knees bent. The person then lifts the head and shoulders in the direction of the knees using the abdominal muscles. The hands may be placed behind the head with the elbows forward so that the elbows touch the knees when the head and shoulders are lifted. The conventional situp, however, places undue stress on the muscles in the lower back, causing discomfort during the exercise and often resulting in an injury.
As a result, the "crunch" style of situp has become a popular alternative to the conventional situp. Crunches are performed in the same manner as conventional situps, except that the head and shoulders are lifted only a limited distance so that less range of motion is required by the muscles in the lower back. Accordingly, the undue stress placed on the muscles in the lower back is not eliminated, but only reduced. In addition, crunches do not optimize the exercise benefit received by the abdominal muscles. In particular, the exercise benefit is lost which obtained by pulling the weight of the head and shoulders the additional distance in the direction of the knees.
A number of weight and "fitness" apparati have been developed recently for exercising the abdominal muscles. These apparati, however, for the most part reproduce the same range of motion as the situp and the crunch. Namely, the resistance produced by the apparatus is concentrated in the lower back and the upper body of the person using the apparatus. One such exercise apparatus is disclosed in U.S. Pat. No. 5,098,089. The '089 apparatus includes a triangular frame for mounting a bed on which the body of the user is supported, knee posts for supporting the knees of the user, and foot posts for receiving the feet and ankles of the user. The frame acts as a fulcrum so that the bed pivots about a transverse axis to permit the user to perform situps with the head elevated above the feet. Accordingly, the user obtains the exercise benefit of the full range of motion of a conventional situp without having to overcome the force of gravity to raise the upper body above the elevation of the feet and knees. Although the '089 exercise apparatus alleviates a portion of the undue stress placed on the muscles in the lower back, it does not increase the exercise benefit obtained by the abdominal muscle groups.
U.S. Pat. No. 5,120,052 to Evans discloses an abdominal exercise apparatus that develops the abdominal muscles through their entire range of motion. The objective of the apparatus is to develop the abdominal muscles not only through contraction, but through increased elongation as well. The apparatus includes a convex arch which engages the upper lumbar and lower thoracic spine in the area of the lower back of the user. The arch permits the user's spine to be supported while allowing the spine to bow outwardly the range that occurs in a normal standing posture. The apparatus further includes an adjustable knee retainer that restrains upward movement of the knees so that the lower back maintains contact with the arch. Accordingly, the range of motion experienced during the situp is increased so that the abdominal muscles are elongated as well as contracted during the exercise. Although the Evans apparatus alleviates a portion of the undue stress placed on the muscles in the lower back and increases the exercise benefit obtained by the muscles in the lower back, it does not significantly increase the exercise benefit obtained by the abdominal muscle groups.
U.S. Pat. No. 5,238,435 to Ricks discloses an exercise apparatus for building stronger stomach muscles. The apparatus includes a pair of foot rests for anchoring the feet of the user in a vertical or inclined orientation. The foot rests immobilize the feet of the user while the user performs a conventional situp. Accordingly, the exercise benefit obtained by the abdominal muscles is somewhat increased by the additional resistance provided by the foot rests. However, the Ricks exercise apparatus placed undue stress on the muscles in the lower back, and only some of the abdominal muscles obtain an increased exercise benefit (i.e., the muscles utilized in performing a conventional situp).
Each of the above exercise apparati place undue stress on the muscles in the lower back and do not provide optimum exercise benefit to all of the abdominal muscle groups. It is apparent that an exercise apparatus that overcomes one or more of the limitations of the exercise apparati described above would be advantageous. In particular, it would be advantageous to provide an exercise apparatus which focuses the benefit of the exercise on all of the abdominal muscle groups, and which does not place undue stress on the muscles in the lower back of the user.
Accordingly, it is an object of the invention to provide an exercise apparatus which works all of the abdominal muscle groups.
It is another object of the invention to provide an exercise apparatus which does not place undue stress on the muscles in the lower back of the user.
It is another, and more particular, object of the invention to provide an exercise apparatus which causes all of the abdominal muscle groups to contract in the direction of the posterior side of the user's body.
It is another object of the invention to provide an exercise apparatus which is lightweight and compact, and thus is convenient to use, transport and store.
The invention disclosed and shown in the accompanying figures provides such an exercise apparatus including additional features which will be more fully described hereinafter.